It has been considered desirable for many years to be able to effectively remove pollutants from the ambient atmosphere in a way such that they will not likely re-enter the environment, and with a minimum of energy input. The invention relates to a method and apparatus for accomplishing that result which is particularly suitable for removing the greenhouse gas carbon dioxide from the atmosphere, establishing the carbon dioxide as a component of a plant fertilizer, and using the fertilizer to treat plants.
The invention is particularly useful for sequestering the greenhouse gas carbon dioxide in a substantially permanent manner. At the same time, other useful work is performed according to the invention so that other objectives can also be met, such as generating electrical energy, pumping liquid, compressing gas, rotating a propeller, or other useful work, and producing fertilizer for application to plants.
According to the invention, it has been determined that potassium containing compounds, such as potassium hydroxide (KOH), and nitrogen containing compounds, such as ammonia (NH3), can be successfully used at ambient temperature and pressure to produce fertilizers by reacting with carbon dioxide in the ambient environment, especially when sufficient moisture is present. The fertilizers produced can be applied directly to land areas where plant growth is desirable, and most of the carbon dioxide will either be taken up by the plants, or sequestered substantially permanently in the soil, especially if the soil has sufficient amounts of calcium and magnesium. [The term “soil” as used herein means any conventional plant growing media]. Some reactions (which are all possible at ambient conditions, even though they might be enhanced at high temperature and/or pressure conditions) that demonstrate these possibilities are:
For potassium:
2 KOH+CO2→K2CO3+H2O [e. g. see U.S. Pat. No. 6,312,655]; and
CO2+K2CO3+H2O→2 KHCO3 [e. g. see U.S. Pat. No. 4,919,910];
or one can start with potassium superoxide (KO2) and the initial reaction will be
4 KO2+2 H2O→4KOH+O2 
For nitrogen:
NH3+CO2+H2O→NH4HCO3 [e. g. see U.S. Pat. No. 6,447,437]
K2CO3 is potassium carbonate and KHCO3 is potassium bicarbonate, and both are known potassium fertilizers that do not have salt buildup (as sometimes occurs when KCl is used as a fertilizer). NH4HCO3 is ammonium bicarbonate, and is a common desirable nitrogen fertilizer. None of these are known to have any significant adverse environmental impact.
In order to practice the invention, preferably a potassium containing compound that will react with CO2 (e. g. potassium hydroxide, potassium carbonate, or potassium superoxide), and/or a nitrogen containing compound that will react with CO2 (e.g. ammonia), are applied to a vane surface of a wind turbine rotor or the like. One desirable way this is done is by applying KOH or ammonia to fabric, which in turn is mounted on, or consists essentially of, a vane of a vertical axis wind turbine (VAWT). The invention also relates to using such a fabric in ambient air flow even if not part of a wind turbine.
When the potassium and nitrogen fertilizers produced as indicated above are applied to soil with plants, the carbonates are partially taken up by the plants and used to produce biomass. In a study done by Cheng et al and reported in the Sep. 18, 2007 “Energy Fuels” Journal, #21, Issue 6, pp. 3334-3340, using ammonium bicarbonate, about 10% of the carbonate was taken up by the plants. As much as 70% of the carbonate reacted with materials in the soil to produce stable compounds (such as calcium carbonate) which sequester the carbon long term, while the relatively small remainder was released back to the atmosphere as carbon dioxide. If the soil is particularly alkaline (e. g. containing significant amounts of calcium and magnesium), then the amount of carbon sequestration by the soil may be substantially maximized. Therefore, the fertilizer application could be accompanied, preceded, or followed by the application of calcium and/or magnesium, or the like, to the soil.
If the air and surroundings at the wind turbine do not have sufficient moisture (certainly where the relative humidity of the air is consistently less than about 40%, or if the climate is particularly dry), then a mist may be sprayed into the path of the rotating vanes of the wind turbine containing the potassium and nitrogen compounds to facilitate the chemical reactions. The mist is typically sprayed using one or more stationary (with respect to vane rotation) nozzles, or comparable structures, positioned adjacent the wind turbine vane path of movement, and spraying may be synchronized with the rotation of the turbine vanes, and interrupted if the wind speed and/or relative humidity exceed a particular threshold, or if the wind speed is below a particular value.
After a sufficient amount of carbon dioxide has been captured by the fabric (which may be sensed by a material which changes color in the presence of carbonates, or determined empirically) of the wind turbine vanes, the fabric is removed. The fabric may be incorporated as is in the soil; or the fabric may be shredded and applied as fertilizer as is, depending upon the type of fabric utilized. Alternatively, the fabric may be burned to produce energy, and the remaining ash—containing the potassium and/or nitrogen compounds—applied to the soil. The ash would have a tendency to make the soil more alkaline, thus likely enhancing the ultimate percentage of carbon sequestration.
While it is highly desirable to use potassium carbonate, potassium bicarbonate, or ammonium bicarbonate according to the invention as a fertilizer, instead they may be used for any other purpose that they commonly are used for. For example, potassium carbonate is often conventionally used in the manufacture of glass, enamels, and soaps. Also, if desired, the starting materials can be regenerated, if this is economical. For example, potassium carbonate can be reacted with calcium hydroxide to produce KOH and calcium carbonate.
According to one aspect of the invention, there is provided a method of removing carbon dioxide from a substantially ambient atmosphere by placing at least one material capable of reacting with carbon dioxide to produce fertilizer in the path of movement of substantially ambient air. When practicing the method the material may comprise a potassium and/or nitrogen containing compound that will ultimately react with ambient carbon dioxide, and the fertilizer produced may be potassium carbonate, potassium bicarbonate, and/or ammonium bicarbonate, and is ultimately put into contact with soil to fertilize plants.
In the practice of the method, the material capable of reacting with carbon dioxide may be associated with a fabric, and the method may comprise placing the fabric in the path of ambient air movement. For example, the method may further comprise placing the fabric and material on a moving portion of a wind turbine; and wherein the wind turbine provides mechanical force; and further comprising utilizing the mechanical force to perform useful work (such as pumping water or other liquid, generating electricity, compressing air or other gas, etc.).
The method may further comprise applying a mist containing water to the material at spaced time intervals if the humidity and/or related conditions are insufficient to provide acceptable reaction conditions, for example if the humidity of the ambient air is less than about 40-50%. Mist application may be practiced using at least one nozzle stationarily, with respect to wind turbine rotation, positioned below the wind turbine and controlled by a controller.
Preferably the fabric is relatively easily biodegradable when in contact with soil (e. g. it is a woven, knit, or nonwoven of natural fibers such as cotton, flax, hemp, etc.), and the method further comprises, after carbon dioxide removal to produce fertilizer, putting the fabric into direct contact with soil, or shredding the fabric and then putting the fabric into contact with soil. Alternatively the method may further comprise burning the fabric to produce useful energy and an ash, and applying the resulting ash to soil.
The starting carbon dioxide removing material may be KOH or ammonia, and the material produced as a result of carbon dioxide removal may be potassium carbonate, potassium bicarbonate, or ammonium bicarbonate. In order to enhance the sequestration of carbon dioxide, the method may further comprise applying calcium and/or magnesium to the soil to which the fertilizer is applied.
According to another aspect of the invention there is provided the combination of: a vertical axis wind turbine having vanes with a material associated therewith capable of reacting with ambient carbon dioxide when sufficient moisture is present; and apparatus which applies a water mist to the material; and wherein the apparatus comprises at least one nozzle controlled by a controller and mounted below the turbine vanes for directing a water mist so that it contacts the material on the vanes. In the combination, the at least one nozzle may comprise a plurality of sets of nozzles, one set of nozzles for each vane of the vertical axis wind turbine. The combination also preferably further comprises an ambient humidity and/or moisture sensor operatively connected to the controller to control the at least one nozzle to apply a mist should the ambient humidity and/or moisture drop below a predetermined level (e. g. below about 40-50%). A wind sensor is also preferably connected to the controller to retard or interrupt mist application if the wind speed is either higher or lower than predetermined thresholds (e. g. greater than 25 mph or less than 5 mph).
In the combination, the at least one nozzle may be movable and the combination may further comprise an actuator controlled by the controller for moving the at least one nozzle to position it to direct water mist in varying directions.
According to another aspect of the invention there is provided a method of removing carbon dioxide from substantially ambient air by placing at least one of a potassium containing compound and a nitrogen containing compound, in a form capable of reacting with carbon dioxide to produce a second potassium or nitrogen containing compound (e. g. potassium carbonate, potassium bicarbonate, or ammonium bicarbonate), in the path of movement of substantially ambient air; and then after carbon dioxide removal from the substantially ambient air, regenerating at least one of a potassium containing compound and a nitrogen containing compound from the second potassium or nitrogen containing compound. Preferably the material capable of reacting with carbon dioxide is associated with a fabric, and the method further comprises placing the fabric and material on a moving portion of a wind turbine; and wherein the wind turbine provides mechanical force and the method further comprises utilizing the mechanical force to perform useful work.
The VAWT is preferably mounted by a portable mounting system which comprises: a drive shaft; a substantially tubular central component; a bearing mounting the drive shaft for rotation within the substantially tubular central component; at least three support legs, at least one of which is telescopic, extending at an angle from the central component and each having a free end; a foot movably mounted adjacent the free end of each of at least two of the support legs; and a load operatively connected to the drive shaft (and which may be operatively connected to at least one of the support legs too). A quick connect/disconnect coupling is provided between the rotor shaft and drive shaft. In order to readily ship the mounting system, an attachment plate may be provided for each leg operatively connected to the central component, and each leg detached from the central component and attachable to an attachment plate by a plurality of fasteners. The attachment plates may be extraneous structures, or may be part of a polygonal (e. g. triangular) shape of the central tubular component.
The VAWT may have particularly designed spokes, for ease of manufacture. According to this aspect there is provided a VAWT spoke curved along a dimension of elongation having a slot substantially along the dimension of elongation for receipt of a vane, the slot open at the free end of the spoke, and closed adjacent the hub of the spoke; and a fastener-receiving opening adjacent the free end of the spoke, which is capable of cooperating with a fastener to hold a vane in the slot.
It is a primary object of the present invention to provide a simple yet effective way to remove carbon dioxide from the air while producing useful materials from it, and preferably while also performing other useful work. (However, the mounting system and wind turbine of the invention may also be used for other purposes). This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.